Elastic power transmission belt



March 1, 1938. ARNOLD 2,109,717

ELASTIC POWER TRANSMISSION BELT Filed May 1, 1936 2 Sheets-Sheet 1 s T 24 1g. l

\nvenTor. Z3 Howard PArnoki b wwkm ATTyse March 1, 1938. H. P. ARNOLDELASTIC POWER TRANSMISSION BELT Filed May 1, 1936 2 Sheets-Sheet 2FiglZ. 341? 33 as 20 "ffnv hTon Howard P Atnoki Patented Mar. 1, 1938UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to an elastic power transmission belt formed byjoining together the ends of a length of belt material, and one objectof the invention is to provide an improved elastic belt, and anotherobject to provide an improved method of making the belt.

The length of belt material from which my improved belt is madecomprises two elastic cords, each cord formed of a plurality of coveredelastic strands twisted together, which cords are twisted together andare connected at the ends of the length, the two twisted-together cordsbeing held in equilibrium or in their twisted-together relation by thetendency of the individual cords to untwist.

In the drawings, Fig. 1 is a fragmentary view of a covered elasticstrand which may be used in making the improved transmission belt.

Fig. 2 shows the first step in the process of making the belt, that is,the formation of a coil from this elastic strand.

Fig. 3 shows the step of twisting the coil to form a twisted cord.

Fig. 4 shows the preliminary step of forming the twisted cord into alength of band or belt material.

Fig. 5 is a fragmentary view of a length of band material from which thecomplete power transmission band is made.

Fig. 6 is a perspective view showing the transmission band.

Fig. '7 is a view similar to Fig. 1 but showing an elastic strand havinga two-ply covering.

Fig. 8 is a figure similar to Fig. 4 but showing a different embodimentof the invention.

Fig. 9 shows the length of belt material made from the cord illustratedin Fig. 8.

Fig. 10 shows a transmission band formed from the length of beltmaterial shown in Fig. 9.

Fig. 11 is a fragmentary view illustrating a fastening device by whichthe ends of the cord are fastened together and also the ends of thelength of belt material.

Fig. 12 is a fragmentary view on a larger scale showing the two ends 2|,22 of a length 20 of belt material fastened together.

In making my improved band I employ an elastic strand I, such as shownin either Fig. 1 or Fig. 7, and which comprises a core member 2 ofrubber or other elastic material and a covering 3 of thread, yarn orsimilar fibrous material which is wound about the core. The covering 3of thread, yarn or similar fibrous material may be a singleply covering,as shown in Fig. 1, or a plural-ply covering, as shown in Fig. '7. Inthe construction shown in Fig. 1 the covering 3 is made by a singlethread 30 which is wound about the cord 2.

In Fig. 7 I have shown a. two-ply covering which is formed by firstwinding a thread 30 about the core 2 in one direction to form the firstply of the covering, and then winding a second thread 3| around thecovered core in the opposite direction to form the second ply of thecovering. Elastic strands with additional plies in the covering may beused if desired.

The first step in the manufacture of the belt is to form a coil 4 ofthis covered elastic strand, the strand being laid in coil formation asshown in Fig. 2 with as many turns or plies 5 in the coil as is desiredfor the size of belt to be made. There may be any number of turns inthis coil and for a small belt a coil having relatively few turns, sayeight or ten, will sufiice, while for a larger belt the coil will bemade with a greater number of turns, say twenty or thirty. After thecoil 4 has been made with the requisite number of turns 5 then the endsof the strand I are knotted or fastened together as shown in 6. The coilis then twisted to produce a twisted cord I, and to do this the coil isplaced over an anchoring book 8, and then the opposite portion of thecoil is placed over a rotary hook member 9 which is shown as rotatablymounted in a suitable support III and is provided with a suitable pulleyII by which it may be rotated. The rotation of the hook 9 twists the twosides of the coil together and thus produces a twisted cord-like elementI. The twisting operation is carried far enough to produce a relativelyhard twist in the cord 1, and during this operation said cord is heldunder sufiicient tension so that it will not kink because of the twistwhich is given to it. After the cord has been given the desired amountof twist it is then removed from the twisting apparatus, and while stillheld under sufficient tension to prevent it from kinking the cord isdoubled and the ends I2 and I3 are fastened together by some suitablefastening device, thereby producing a two-ply cord having one-half thelength of the cord I as it was removed from the twisting apparatus. Oneway of connecting the two ends I2 and I3 of the twisted cord is shown inFig. 4 wherein said ends I2 and I3 are connected by a fastening deviceI4, and the doubling operation is performed in such a way that theconnected ends I2, I3 will be located intermediate of the ends of thedoubled element so that the two ends I6, II of the doubled cord are inthe form of loops, and the two plies or sections of the double cord arethus integrally conected at each end.

In Fig. 4 the twisted cord I is shown as passed ends l2 and I3 connectedtogether by the fastening device It, the retaining members I! serving tohold the cord from kinking due to the twist therein.

'Ihe fastening device It may be. a wire or a thread or small cord whichis threaded through the openings in the ends of the twisted cord 1 whichwere occupied by the hooks 3, 9. After the ends I2, I 3 of the cord Ihave been fastened together and the cord has been doubled as shown inFig. 4, then the doubled cord is released at one or both ends, and thetendency of each of the two sections ll, |9.to untwist will cause saidsections to twist together to produce the twisted belt member 20 shownin Fig. 5. This twisting together of the two sections l8, I! willcontinue until the belt material reaches a state of equilibrium in whichthe tendency of each of the separate sections i8 and I! to untwist iscounterbalanced by the tendency of the twisted belt ele ment 20 tountwist.

There is, therefore, provided an elastic belt element 20 comprising thetwo sections l8 and I9 twisted together, which sections are integrallyconnected at the ends 2| and 22 of the length 20 of belt material.Furthermore each of the sections or cord elements |8, |9, which beingtwisted together form the length 20 of belt material, is composed of aplurality of elastic strands twisted together.

After the length 20 of belt material has been thus formed the ends 2|,22 thereof are fastened together by a suitable fastening 23, therebyform-' ing an elastic belt or band 24 adapted for power transmissionpurposes. The fastening device 23 may be of any suitable type such as awire or a thread or cord my which the ends 2|, 22 are tied together.

In Figs. 8 to 11-I have shown a different embodiment of the inventionwherein the fastening device by which the ends l2, l3 of the cord 1 arefastened also constitutes the fastening means by which the ends 2|, 22of the length 20 of belt material are fastened together.

This fastening device is indicated at 33 and it is preferably made ofwire and comprises the loop portion 24 by which the ends l2, I3 arefastened together, and the hook portion 35 by which the ends 2|, 22 arefastened together.

In making the belt in accordance with what is shown in Figs. 8 to 11 thecord 1 is doubled so that the two ends l2, l3 will be located at the endof the double cord, as shown in Fig. 8. These ends l2, l3 are fastenedtogether by the loop portion 34 of the fastening device 33 in the samemanner that the ends I2 and I3 are fastened together by the fasteningdevice II. The fastening device 33 is made, in the first instance, withthe loop portion 34 partly open, and the end 3 of the loop is threadedthrough the openings in the ends |2, I3 of the twisted cord'l which wereoccupied by the hooks I and I. The loop 34 may then be closed, ifdesired, to retain each end of the cord 1 in said loop. with thisarrangement the fastening device 33 will be located at the end of thedouble cord, and when the double cord is released to allow the twosections I8 and I8 thereof to twist together a length 23.

Since the two cord members i8 and I! which are twisted together to formthe belt material 20 are in themselves formed of elastic strands twistedtogether, the resulting belt will be an elastic belt which is admirablyadapted for various power transmitting purposes and especially for usein machines where the belt-driven member is running at a high speed.

A transmission band embodying this invention is very flexible andbecause of its elastic characteristics it will always be tight on thepulley. A belt having this construction will rotate a driven member athigh speed with less expenditure of power than belts now commonly usedfor this 1 1111 088.

I claim:

The method of making a power transmission band which consists in forminga single continuous strand having an elastic core and a covering offibrous materialinto a coil having a multiplicity of parallel contiguousturns, fastening the ends of the length of the strand together, formingthe coil into an elongated loop, twisting together the two sides of theloop to form 'a rela- .tively hard twisted cord, doubling the hardtwisted cord and connecting the ends together while maintaining the cordunder suflicient tension to prevent it from kinking due to the twisttherein, releasing one end of the doubled cord whereby the two cordmembers become twisted together by the tendency of each cord member toun'twist and a length of two-ply twisted belt material is produced whichis held in a state of equilibrium due to the tendency of the twistedlength of belt material to untwist being counterbalanced by the tendencyof the individual cord members to untwist, and then connecting togetherthe two ends of the length of two-ply twisted belt material.

' HOWARD P. ARNOLD.

